Sucking is a precocial motor behavior in humans. However, premature infants often demonstrate oromotor dyscoordination and are unable to suck or feed orally. This inability to feed can delay discharge from neonatal intensive care units and hinder development of coordinated oromotor behavior.
Infants' readiness to feed is often evaluated by their display of non-nutritive sucking (NNS). Suck is manifest in-utero between 15 and 18 weeks gestation age (GA). NNS typically begins between 28 and 33 weeks GA and is remarkably stable by 34 weeks. Non-nutritive suck normally comprises a series of suck activity bursts separated by pauses. Each burst consists of 6 to 12 suck cycles that occur at approximately 2 Hz and are separated by pauses for respiration. The mammalian NNS is primarily controlled by the suck central pattern generator (sCPG), which includes bilateral internuncial circuits within the brainstem reticular formation. The minimal circuitry for ororhythmic activity resides between the trigeminal motor nucleus and the facial nucleus in the brainstem.
Some patients, including, but not limited to pre-mature infants, often demonstrate oromotor discoordination and are unable to suck and feed orally. Oromotor discoordination represents challenge to neonatal care unit survivors and the survivor caretakers. Potential causes of oromotor discoordination or impaired suck development are numerous and include, but are not limited to, neurological insult to the developing brain, feeding intolerance and interventions that interfere with ororhythmic pattern formation. For example, lengthy oxygen supplementation procedures can interfere with ororhythmic pattern formation.
In current practice, infant NNS evaluation is still quite subjective. Typically, NNS is evaluated by placing a gloved finger in the infant's mouth to observe the rhythmicity, strength, cycle frequency, and burst duration of NNS. Clinical observations can then be characterized with validated scales, such as the NOMAS®, which are designed to assess sucking patterns in preterm infants and monitor changes over time, or the Early Feeding Skills (EFS) Assessment, which is a checklist of suck-swallow coordination and physiological stability.
An objective and quantitative measure of oromotor ability would greatly benefit neonatal intensive care diagnostics and treatment.